Logisim, a graphical design and simulation tool for logic circuits, has now reached version 2.1.3. This version introduces an Input/Output library, including a button, a LED, and a 7-segment display - components that often appear in simple circuits that interface with users. The new version also adds rotation capability to the components of the Plexers library, it allows the user to configure where in the window the toolbar is placed, and - of course - it repairs a handful of bugs.
Educational institutions around the world use Logisim as an aid to teaching about digital logic and computer architecture. As a Java application, Logisim can run on most major operating systems. Read more about Logisim at http://www.cburch.com/logisim/, and download it from SourceForge.net at http://sourceforge.net/projects/circuit/.